Problem: $ { \left[\begin{array}{rrr}{1} & {4} & {2} \\ {0} & {2} & {0}\end{array}\right]-\left[\begin{array}{rrr}{-2} & {4} & {-1} \\ {2} & {0} & {-1}\end{array}\right] = {?} } $
Solution: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rrr}{1}-{-2} & {4}-{4} & {2}-{-1} \\ {0}-{2} & {2}-{0} & {0}-{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{3} & {0} & {3} \\ {-2} & {2} & {1}\end{array}\right]}$